title: Interaction of a synthetic antimicrobial peptide with model membrane by fluorescence spectroscopy.
abstract: Static and time-resolved fluorescence of tryptophan and ortho-aminobenzoic acid was used to investigate the interaction of the synthetic antimicrobial peptide L1A (IDGLKAIWKKVADLLKNT-NH2) with POPC and POPC:POPG. N-acetylated (Ac-L1A) and N-terminus covalently bonded ortho-aminobenzoic acid (Abz-L1A-W8V) were also used. Static fluorescence and quenching by acrylamide showed that the peptides adsorption to the lipid bilayers was accompanied by spectral blue shift and by a decrease in fluorescence quenching, indicating that the peptides moved to a less polar environment probably buried in the lipidic phase of the vesicles. These results also suggest that the loss of the N-terminus charge allowed deeper fluorophore insertion in the bilayer. Despite the local character of spectroscopic information, conclusions can be drawn about the peptides as a whole. The dynamic behaviors of the peptides are such that the mean intensity lifetimes, the long correlation time and the residual anisotropy at long times increased when the peptides adsorb in lipid vesicles, being larger in anionic vesicles. From the steady-state increase in fluorescence intensity and anisotropy, we observed that the partition coefficient of peptides L1A and its Abz analog in both types of vesicles are higher than the acetylated analog; moreover, the affinity to the anionic vesicle is higher than to the zwitterionic.
authors.affiliation: Department of Physics, IBILCE, UNESP, São Paulo State University, Rua Cristovão Colombo 2265, São José do Rio Preto, SP, 15054-000, Brazil.
authors.forename: Luciana Moro Puia
authors.initials: LM
authors.lastname: Zanin
authors.forename: Dayane
authors.initials: D
authors.lastname: Dos Santos Alvares
authors.forename: Maria Aparecida
authors.initials: MA
authors.lastname: Juliano
authors.forename: Wallance Moreira
authors.initials: WM
authors.lastname: Pazin
authors.forename: Amando Siuiti
authors.initials: AS
authors.lastname: Ito
authors.forename: João
authors.initials: J
authors.lastname: Ruggiero Neto
mesh_terms: D000595:Amino Acid Sequence; D000890:Anti-Infective Agents / Q000138:chemical synthesis / Q000737:chemistry / Q000378:metabolism*; D002462:Cell Membrane / Q000737:chemistry / Q000378:metabolism*; D008051:Lipid Bilayers / Q000737:chemistry / Q000378:metabolism; D008969:Molecular Sequence Data; D010455:Peptides / Q000138:chemical synthesis / Q000737:chemistry / Q000378:metabolism*; D010743:Phospholipids / Q000378:metabolism; D011485:Protein Binding; D012997:Solvents / Q000737:chemistry; D013050:Spectrometry, Fluorescence; D014867:Water / Q000737:chemistry
chemical_list: D000890:Anti-Infective Agents; D008051:Lipid Bilayers; D010455:Peptides; D010743:Phospholipids; D012997:Solvents; D014867:Water